<!DOCTYPE html>

<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>透明度问题</title>
        <style type="text/css">
            body { background-color: #dedede ; }
            .wrapper { border: 1px solid blue ; width: 50% ; margin: 25px auto ;}
            .parent {  background-color: #1e9fff;  }

            .child {  height: 100px ;  }
            .first { background-color: #9932CC ; opacity: 1!important; ;  }
        </style>
    </head>
    <body>

        <div class="wrapper">
            <div class="parent">
                <div class="child first"></div>
                <div class="child second"></div>
            </div>
        </div>
        
    </body>
</html>